Television apparatus



Oct. 11, 1938. K. 'rll-IANYI TELEVISlON APPARATUS Original Filed June 10, 1929 INVENTOR LMAN a IHANYI ATTORNEY ducer. To this end the system is so designed and Cil Patented Oct. 11, 1938 UNITEDSTATES TELEVISION I Kalman Tihanyl, Budapeshllungary, Vassigner to Radio Corporation of America, a corporation y of Delaware` Original application 369,598. Di'videdand 1935, Serial No. 9,959.

s claims. (ci. 11s-1.5i

i The present invention relates` to television apparatus, and is particularly directed to the receiver end of the system. This application forms Vaclivsional part of my copendinggapplication- Serial No. 369,598, iiled June 10, 1929, for an invention entitled Television apparatus.

It is one of the primary objects of the present invention to eliminate many of the dimculties which arise in connection with the methods of reproducing television images as heretoforepracticed in the art, with particular reference being had to the diiculties which have arisen in connection with the so-called mechanical types of television apparatus such, for example, as the Nipkow disc. Also in the prior art, so far as I am aware, diiculties, havefrequently arisen due to the fact that it has been substantially impossible to cause the produced electro-optical effccts to persist for any appreciable length of time. Therefore, in accordance with my present invention recourse is had to systems wherein special means are provided for intensifying the picture resulting in. the receiving tube of the system assuming the invention to be applied to the so-called cathode ray type of .image reprodeveloped that there is produced in the receiver tube the effect of storage of the image producing signals so that the electro-optical eiects which result are maintained substantially throughout the entire scansion cycle.

Other objects and advantages of the' invention are to provide improved television reproducing apparatus which will be eflicient in its operation, and easy to control.

Still otherobjects and advantages will be apparent to those skilled in the art by a reading of the following specification and claims taken ,in connection with the accompanying drawing wherein:

Fig. 1 discloses an arrangement wherein a gridlike strucfure is combined with an electrode for emitting electrons to control the brilliance of the fluorescent effects resulting;

Fig. 2 shows a modification of the arrangement of Fig. 1; v

Fig. 3 illustrates a still further modiiication;

and

Fig. 4 shows, for example. one form ofgrid structure which'might be used in connection with the apparatus disclosed by Fig. 1 although other forms of grid structure could be substituted.

In making reference to the accompanying drawing, image signals transmitted by any desired Atype of transmitting apparatus such, for example, as that shown in my parent application Serial No. 369,598 above referred to, are suitably received in a receiving device I and are supplied to the control electrode system 3 of a cathode ray tube conventionally designated 5. Within this "June 1o, ,1929, serial No.

this application March 8, In Germany June 1l,

` tube, there is developed between a cathode I and an anode 9 anvelectron beam conventionally designated II whose intensity is controlled in accordance with the strength of the received signal applied to the control gridA 3. At the opposite end of the tube 5. there is provided a iluorescent screen structure i3, and intermediate this screen structure and the point at which the electron beam II is developed, there is provided a source of electrons which is provided by meansof a series of cathode wires or some other appropriate emitter I5. The electrons emitted from the source I5 tendto ow toward the screen structure I3 by reason of the voltage difference maintained between the emitter I5 and the screen I3 by the battery I1 so that in the absence of any cathode ray II developed within the tube, there will be substantially constant intensity light produced upon the fluorescent screen structure. Intermediate the emitting surface I5 and the screen I3 there is provided a grid-like structure I9 which, for example, may be of the form shown by Fig. 4 so arranged the grid structure I9 comprises an internal conducting member 2i about which is a layer of insulating material 23 extending throughout the entire length of the conductor. Covering the insulator 23 and spaced apart from each other are a plurality of electrically isolated photoelectric areas 25. With the arrangement as described, the electron beam Il developed within the tube passes through the emitter element I5 so as to impinge upon the photoelectric surface 25 and the associated insulator 23 in the area intermediate the independent photoelectric areas. When this happens, itis believed that the positive charge which the photoelectric areas acquire due to the illumination of the screen structure I3 as produced by Vthe electrons from the source I5 impinging upon the same will be neutralized, and thus the in tensity of the fluorescent effect resulting will be modied. The charge produced by virtue of the impact of the beam electrons as controlled in intensity by the signal applied to the control grid 3 will vary the intensity of illumination upon the screen structure I3 so that it is proportional to the signal received. This intensity of fluorescent eiect will continue during the time interval between successive scansions by the beam.

The scanning action takes place by virtue of any s 'table controlling voltages applied to the deilecting systems 21 and 29 which, itv may be assumed, are in synchronism with similar controlling voltages at the transmitter end of they electron beam developing arrangement comprising the cathode 1 and the anode 9, two additional electrodes which comprise cathode wires. such as that shown at 3| and a photoelectric layer such as that shown at 33. The layeror gridl 33 with its electric eld elements inuencing the intensity of the electron Y wires 3l in a manner substantially similar to that oi the ordinary type of two-plate valve in which the cathode is between an anode andan opposite electrode. The grid-like structure 33 and the electrode 3| may also be arranged behind the screen where desired. Any negative charges on the photoelectric grid 33 must be removed or neutralized after the conductor has been transmitted, andthis may be done by iridation with homogeneous light, for example, as indicated conventionally by means of the infalling light rays designated as 35, and the photoelectric effect which is released thereby will cause the entire grid to be charged to a positive tension, for example, the limit tension, and is then ready for the next operation or, in other words, the next cycle of scansion, and the electrodes released by the homogeneous light beams may be accumulated in any positive portion of the tube, for example, the screen structure itself.

A still further modication of the arrangement, as disclosed by Fig. 3, a cathode is shown at the rear of the fluorescent screen I3. In this showing, 31 represents an insulated plate on the front face of which layers of photo-sensitive material 39, as described above, are provided. Opposite the layers of photo-sensitive material 39 are .similar layers @l which are arranged on the face of the plate 31 which is not struck by the developed cathode ray beam il. The screen structure I3 with its phosphorescent layer is arranged on the rear face of the system, and electrodes which radiate electric particles, such as the cathode element d3, may be arranged at the rear of the system. The cathode wires are preferably made from a metal having a low cathode drop, and the tube is lled with a rare gas, such as argon, for

example, at low pressure. The wires may also be of oxide in red hot condition, and may be coated, for example, with barium oxide. As described in connection with the description of Fig. 3, homogeneous light from a suitable source 35 may be arranged to neutralize the charges at the completion of each cycle of scansion.

While the invention. has been illustrated in several of its preferred forms it will, of course, be apparent that many additional modifications may be made without departing from the spirit and scope of the aforegoing disclosure.

Having now described one form of the invention and the manner in which it is believed the same may be operated, what is claimed and desired to secure by Letters Patent is the following:

1. In a television apparatus, a cathode ray tube having means at one end thereof to develop an electron beam, an image carrier at the other end of the tube, said image carrier comprising a network of electrically conducting strands having insulating material surrounding each, a plurality of separated light sensitive areas supported upon the insulators, a fiuorescent screen and a source of electrons each positioned adjacent said image carrier, and on opposite sides thereof.

2. A cathode ray tube comprising an evacuated envelope containing a screen structure adapted current from the cathode ated envelope containing a screen structure adapted to .fiuoresce under electronic bombardment, a homogeneous source of electrons substantially adjacent the screen structure, a control electrode intermediate the electron source of the screen structure, said control electrode comprising a network of electrically conducting strands having insulating material surrounding each, and a plurality of separated light sensitive elemental areas supported upon the insulators, means to produce a cathode ray `beam and to control the intensity thereof in accordance with received image signals, and means for causing the iniensity controlled cathode ray beam to scan said control electrode to produce at each said light sensitive elemental area thereof during scansion an electrostatic charge to modify the illumination intensity normally produced on said screen structure.

4. In an electron tube of the cathode ray type including an evacuated envelope, a cathode at one end thereof. and an anode to which appropriate voltages are adapted to be applied so as to develope an electron beam, an image carrier in the opposite end of the envelope, said image carrier comprising a network of electrically conducting strands having insulated material surrounding each, a sensitive elemental areas supported upon the insulators, a fluorescent screen positioned adjacent to and on one side of said image carrier, and a source of electrons positioned on the other side of said image carrier.

5. An electron tube of the cathode ray type including an evacuated envelope. a cathode at one end thereof and an anode to which appropriate voltages are adapted to be applied so as to develop an electron beam, a fluorescent screen structure adapted to fluoresce under electronic bombardment positioned in the opposite end of. the evacuated envelope, a source of electrons substantially adjacent said screen structure, a control electrode adapted to control the flow of electrons from said source to said screen structure, said control electrode comprising a plurality of electrically conducting strands having insulating material surrounding each, and a plurality of separated elemental light sensitive areas supported upon the insulators, means for controlling the intensity of the devloped electron beam in' structure.

TIHANYI.

plurality of separated light` produce at each elementalv Ato fluoresc underv electronicl bombardment, a y 

